Hybrid temperature control system

ABSTRACT

A method of operating a hybrid temperature control system. The method provides an evaporator, which has a discharge line, a supply line, and a evaporator coil. The evaporator coil is in fluid communication with the discharge line and the supply line. The method also provides a microprocessor, which regulates a supply of a heat absorbing fluid to the evaporator. The method further couples a sensor module to the microprocessor. The sensor module is near the evaporator, senses a temperature of a gas exiting the evaporator, and sends a temperature to the microprocessor. The method also turns off the supply of the heat absorbing fluid to the evaporator when the microprocessor determines that the temperature of the gas exiting the evaporator reaches a predetermined temperature.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U.S.C. § 119 to aprovisional patent application serial No. 60/293,481, filed on May 25,2001.

BACKGROUND OF THE INVENTION

[0002] The invention relates to a temperature control system for pullingdown the temperature in a conditioned space to a set point temperature,and for maintaining the set point temperature of the conditioned space;and more particularly the invention relates to a hybrid temperaturecontrol system that includes a first evaporator coil which utilizes afirst heat absorbing fluid to provide primary temperature control of theconditioned space air and a second evaporator coil adjacent to, adistance from, or integrated with , the first evaporator coil where thesecond evaporator coil utilizes a second heat absorbing fluid to providesupplemental temperature control of the conditioned space air.

[0003] Mobile temperature control units are typically mounted on one endof trailers, trucks or containers to maintain the cargo transported inthe trailer, truck, or container conditioned space at a desired setpoint temperature during shipment. Known temperature control units maybe mechanical units which utilize a hydroflurocarbon-based refrigerantto maintain the conditioned space ambient fluid at the desired set pointtemperature. As illustrated schematically in FIG. 1, prior artmechanical temperature control unit 10 is generally comprised of acompressor 11 that raises the pressure of a known refrigerant gas, acondenser 12 flow connected to the compressor to condense the highpressure refrigerant gas to a liquid, and an expansion valve 13 forcontrolling the refrigerant flow to an evaporator 14. The evaporator 14includes evaporator coils 17 which are enclosed by an evaporator housing20 having an evaporator inlet 16 through which conditioned space airenters the evaporator and an evaporator discharge 18 through whichconditioned space air reenters the conditioned space.

[0004] Warm conditioned space air flows into the evaporator inlet 16,continues across the evaporator coils 17 and is discharged throughevaporator discharge 18. The refrigerant that flows through theevaporator coils 17 absorbs heat from the conditioned space air, and inthis way pulls down the temperature of the conditioned space air to apredetermined set point temperature and thereby maintains theconditioned space at the set point temperature.

[0005] In operation, high cooling capacities are needed to pull down ahigher temperature conditioned space to the desired lower set pointtemperature in a relatively short time. After the conditioned space hasbeen pulled down to the desired set point temperature, the coolingcapacities required to maintain the conditioned space set pointtemperature are modest relative to the required pull down coolingcapacities.

[0006] Conventional mechanical temperature control units provide therequired variable cooling capacities by utilizing a compressor primemover (not shown in FIG. 1) that drives the compressor at high and lowspeeds to provide high and low cooling capacities. However, even knownmechanical temperature control units that utilize multi-speed primemovers cannot provide the cooling capacities required during peak demandperiods. For example, during transportation of cargo, the doors to thetrailer or truck are typically left open while the cargo is unloadedfrom the conditioned space. The temperature of the cargo conditionedspace increases as the warm outside ambient air flows into the trailerconditioned space. The doors may be left open for an hour or more duringunloading. After the delivery has been made and the doors are againclosed, the conditioned space is pulled down to reestablish theconditioned space set point temperature. If the temperature of theconditioned space is not pulled down quickly, the load can spoil. Knownmechanical units cannot provide the cooling capacity needed to quicklyinitially pull down the conditioned space or reestablish the set pointtemperature after cargo unloading.

[0007] In order for known mechanical units to achieve the desired pulldown capacities, the size of conventional mechanical refrigeration unitswould need to be increased considerably. However this is not a realisticalternative since such units would be too large to be effectively usedin the trailer, truck or container applications and such larger capacitymechanical units would be higher in cost, would be less efficient, wouldweigh more and would be noisier than conventional mechanical units.

[0008] A non-mechanical temperature control unit has been developed tomeet the peak cooling demands at initial pull down and during pull downto reestablish the set point temperature in the conditioned space. Suchnon-mechanical temperature control units utilize a cryogen fluid toproduce the desired cooling in the conditioned space. FIG. 2schematically illustrates a prior art cryogen-based temperature controlsystem 30 that includes a supply of cryogen liquid in cryogen tank 32and the cryogen may be liquid carbon dioxide LCO₂ for example. Anelectronic expansion valve 34 or other valve means regulates the supplyof cryogen through the evaporator coil 38 of evaporator 36. Amicroprocessor 37 adjusts the expansion valve position by sending asignal to the valve in response to the sensed temperature at theevaporator unit 36. A vapor motor 40 drives a fan 45 that drawsconditioned space air through the evaporator 36 and across theevaporator coil 38. The rotating vapor motor turns alternator 41 whichcharges a temperature control unit battery (not shown).

[0009] The higher temperature conditioned space air is drawn into theevaporator and across coil 38. The cryogen liquid flowing through theevaporator coil absorbs heat from the conditioned space air and thelower temperature air is discharged from the evaporator 36 into theconditioned space in the direction of arrows 43. The cryogen isvaporized as it absorbs heat from the conditioned space air. The cryogenvapor flows out of the evaporator and drives the vapor motor 40. Thespent cryogen vapor is exhausted from the vapor motor to atmospherethrough exhaust 42 and muffler 39.

[0010] The liquid cryogen can provide the cooling capacity required toquickly pull down the conditioned space. However, there are limitationsassociated with non-mechanical, cryogenic based temperature controlunits. First, cryogen units are limited by how fast one wants to dropthe cargo temperature and by practical considerations so that freshloads such as produce are not frozen. The supply of cryogen typicallyonly lasts one to three days and when the cryogen supply is exhaustedthe tank must be refilled. It may be difficult to locate a cryogenfilling station. If the cryogen units are to provide defrost and heatingcapability, a heating fuel and necessary heating components must beprovided.

[0011] Hybrid mechanical and non-mechanical temperature control systemshave been developed. These systems directly spray a volume of cryogeninto the conditioned space during pull down of the conditioned space tothe set point temperature. As a result, the conditioned space air isdisplaced and the conditioned space is comprised primarily of cryogen,which is undesirable for most applications. The cryogen is notbreathable and can negatively affect some foods.

[0012] The foregoing illustrates limitations known to exist in presentdevices and methods. Thus, it is apparent that it would be advantageousto provide an alternative directed to overcoming one or more of thelimitations set forth above. Accordingly, a suitable alternative isprovided including features more fully disclosed hereinafter.

SUMMARY OF THE INVENTION

[0013] In one aspect of the present invention, this is accomplished byproviding a hybrid temperature control system including a mechanicaltemperature control system that includes a primary evaporator having afirst evaporator coil with a first heat absorbing fluid adapted to flowthrough the first coil to absorb heat from the conditioned space air andprovide primary cooling of the conditioned space air. The hybridtemperature control system further includes a supplemental evaporatorlocated adjacent to, a distance from, or integrated with the firstevaporator coil. The supplemental evaporator includes a supplementalevaporator coil with a second heat absorbing fluid adapted to flowthrough the supplemental evaporator coil to provide supplemental coolingof the conditioned space air.

[0014] The first heat absorbing fluid is a conventional refrigerant andthe second heat absorbing fluid is a cryogen.

[0015] By the present invention supplemental cooling of the conditionedspace air by the supplemental evaporator is controlled by amicroprocessor or by the unit operator so that supplemental cooling isonly provided when required such as during initial pull down of theconditioned space or during pull down to reestablish the conditionedspace set point temperature.

[0016] The supplemental evaporator coil may be made integral with themechanical refrigeration unit evaporator housing with the supplementalevaporator coil located immediately adjacent to the primary evaporatordischarge. Additionally, the supplemental evaporator coil may be locatedadjacent to, a distance from, or integrated with the mechanicalevaporator discharge by locating the coil on a panel of the conditionedspace, such as the ceiling; or along side the primary evaporator coil.

[0017] The invention may be utilized in both a conditioned space to bemaintained at a single set point temperature and also inmulti-temperature applications having a first conditioned space to bemaintained at a first temperature with a first primary evaporator and afirst supplemental evaporator adjacent to, a distance from, orintegrated with or along side the first primary evaporator; and secondconditioned space at a second set point temperature with a secondprimary evaporator, and a second supplemental evaporator adjacent to, adistance from, or integrated with the second primary evaporator.

[0018] When the present invention is used in a multi-temperatureapplication with a number of conditioned spaces, any of the conditionedspaces may be maintained at the lowest set point temperature.

[0019] The foregoing and other aspects will become apparent from thefollowing detailed description of the invention when considered inconjunction with the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the drawings:

[0021]FIG. 1 is a schematic representation of a conventional mechanicaltemperature control system;

[0022]FIG. 2 is a schematic representation of a conventionalnon-mechanical, cryogen-based temperature control system;

[0023]FIG. 3 is a systematic representation of a first embodiment of thehybrid temperature control system of the present invention;

[0024]FIG. 4 is a longitudinal sectional view of a conventional trailerincluding the hybrid temperature control unit of FIG. 3;

[0025]FIG. 4A is a longitudinal sectional view of a conventional trailerincluding the hybrid temperature control unit of FIG. 3 with the exhaustline in the front;

[0026]FIG. 5 is a systematic representation of a second embodiment ofthe hybrid temperature control system of the present invention;

[0027]FIG. 6 is a longitudinal sectional view of a conventional trailerincluding the second embodiment hybrid temperature control system ofFIG. 5;

[0028]FIG. 7 is a longitudinal section view of a conventional trailerillustrating a third embodiment hybrid temperature control system of thepresent invention.

[0029]FIG. 8 is a systematic representation of a fourth embodimenthybrid temperature control system of the present invention.

DETAILED DESCRIPTION

[0030] Before any embodiments of the invention are explained in detail,it is to be understood that the invention is not limited in itsapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in thefollowing drawings. The invention is capable of other embodiments and ofbeing practiced or of being carried out in various ways. Also, it is tobe understood that the phraseology and terminology used herein is forthe purpose of description and should not be regarded as limiting. Theuse of “including,” “comprising,” or “having” and variations thereofherein is meant to encompass the items listed thereafter and equivalentsthereof as well as additional items.

[0031] Turning now to the drawings wherein like parts are referred to bythe same number throughout the several views, FIGS. 3 and 4 illustrate afirst embodiment of the hybrid temperature control system 50 of thepresent invention. As shown in FIG. 3, the hybrid temperature controlsystem 50 is comprised of the mechanical temperature control system 10as previously described hereinabove and supplemental cooling unit 52adjacent to, a distance from, or integrated with mechanical evaporatorcoil 17.

[0032] As the description proceeds, the supplemental cooling unit 52will be described as being manually actuated. It should be understoodthat it is also contemplated that a microprocessor or other suitableelectronic means will actuate the unit 52.

[0033] As illustrated in FIG. 3 the evaporator housing 20 of FIG. 1 maybe extended and the extended housing is identified at 54. The housingincludes inlet 16 and discharge opening 55. A supplemental evaporatorcoil 56 is located in the housing extension adjacent to, a distancefrom, or integrated with the evaporator coil 17. Although one row ofcryogen evaporator coils 56 is shown in FIGS. 3 and 4 it should beunderstood that additional rows of coils 56 may be provided.

[0034] The heat absorbing fluid in supplemental cooling unit 52 is acryogen liquid that is stored in cryogen tank 32. The cryogen liquidflows through the supplemental evaporator coil and is vaporized in thesupplemental coil during operation of unit 50. The supply of liquidcryogen through the supplemental evaporator coil 56 is controlled byvalve 58 flow connected along the length of the inlet line 60 that flowconnects the cryogen tank and the cryogen evaporator coil 56. The valve58 may be any suitable valve well known to one skilled in the art suchas a manually actuated butterfly valve or may be an electronic expansionvalve for example. However, the suitable valve 56 permits forselectively supplying cryogen to coil 56 and adjusting the volume ofcryogen provided to the coil. A conventional back pressure regulator 62is located in exhaust line 64. The regulator 62 may be an electronicallya manually or a spring actuated back pressure valve. The inlet line 60is located in a front trailer panel 81, a bottom panel 84 and passesthrough the bottom panel 84. See FIG. 4.

[0035] It should be understood that valves 58 and 62 and associatedlines 60, 64 are shown schematically in FIGS. 3 and 4 for illustrativepurposes only and the valves may be located in unit 50 with associatedflow lines located in the trailer panels.

[0036]FIG. 4 illustrates the first embodiment hybrid temperature controlunit of the present invention 50 mounted for use on the nose of trailer80. The trailer includes front 81, top 82, rear 83, bottom 84, and sidepanels 85 that define a conditioned space 88. The cryogen tank 32 andthe fuel tank 33 for the compressor prime mover are mounted on thebottom side of the trailer in a conventional manner. The exhaust line 64extends through the trailer top panel 82, side panel 85, and the flowline 64 passes through the bottom panel 84. The exhaust line 64, in thepreferred embodiment shown in FIG. 4A, extends through the cryogenicunit 50 in the front. A conventional fuel supply line 75 flow connectsfuel tank 33 and the prime mover (not shown) of mechanical unit 10.

[0037] Although conditioned space 88 is shown and described as beingdefined by a trailer, it should be understood that the conditioned spacecould be defined by a truck, container, bus, railway car, warehouse,storage facility, repository, storehouse or other enclosed volume orspace, mobile or stationary, requiring the temperature in the enclosedconditioned space to be maintained at a predetermined set pointtemperature.

[0038] Operation of the first embodiment hybrid temperature control unit50 of the present invention will now be described. When the mechanicalunit is in high speed cool mode, it signals that supplemental cooling bysupplemental evaporator coil 56 is needed to provide rapid pull down ofthe air in the conditioned space 88. Then after a period of time, valve58 is opened either electronically or manually to permit liquid cryogento flow from tank 32 through line 60 to supplemental evaporator coil 56.The mechanical temperature control unit 10 is started before the valve58 is opened.

[0039] Higher temperature conditioned space air is drawn through inlet16 and across the primary evaporator coils 17. The refrigerant flowingthrough the coils 17 absorbs heat from the conditioned space air andthereby provides primary cooling to the conditioned space air. The lowertemperature conditioned space air continues across supplementalevaporator coils 56. The cryogen flowing through the supplemental coilsabsorbs additional heat from the already cool conditioned space air.After passing the coils 56 the cooled ambient air is discharged fromhousing 54 through opening 55 back into conditioned space 88. Thevaporized cryogen is exhausted out exhaust 64 to atmosphere. None of thevaporized cryogen enters the conditioned space.

[0040] The supplemental cooling can be stopped manually or with a timerto automatically shut off the flow of cryogen. The valve “on” timevaries for each particular application and is generally dependent on theambient conditions, cargo, and required conditioned space set pointtemperature. The supplemental cooling may be shut off by a temperatureswitch.

[0041] The supplemental evaporation provided by supplemental evaporatorcoil 56 provides rapid pull down of conditioned space 88. Because thecryogen is released to atmosphere the cargo in the space 88 is notexposed to cryogen gas. The application of supplemental cooling may beselectively applied to meet peak demand such as during pull downs.Therefore, frequent refills of the cryogen tank are not required.

[0042] A second embodiment hybrid temperature control unit 90 isillustrated in FIGS. 5 and 6. The second embodiment unit 90 includesmechanical unit 10 as previously described hereinabove and also includessupplemental cooling unit 92. The supplemental cooling unit is adaptedfor use with trailer 80 also previously described.

[0043] The supplemental cooling unit is comprised of cryogen tank 32with flow of the cryogen from the tank being regulated by valve 58. Asupplemental evaporator 93 is mounted on the interior of trailer roofpanel 82 in conditioned space 88 adjacent to, a distance from, orintegrated with the evaporator 17 of mechanical temperature control unit10. The evaporator 93 may also be located along side evaporator 14. Thesupplemental evaporator is mounted on the roof panel in a conventionalmanner. The supplemental evaporator 93 has a supplemental evaporatorcoil 94 that is flow connected to supply line 95 and discharge line 96that extends through roof 82 to atmosphere. Valve 58 is connected tosupply line 95 outside the conditioned space. The supply line passesthrough the bottom panel of the trailer 80. The back pressure regulator62 is located in the discharge line 96 outside the trailer conditionedspace. Although line 96 is shown extending in panel 88 and line 95extending through panel 85 and bottom panel 84 with valves 58 and 62located outside the trailer, the lines and valves may assume anysuitable configuration and location.

[0044] It is easy to retrofit existing mechanical temperature controlunits with supplemental cooling units 92 by mounting the supplementalevaporator adjacent to, a distance from, or integrated with evaporator14 in the flow path of the mechanical unit evaporator, and by connectingthe associated supply and discharge flow lines to the supplementalevaporator coil.

[0045] The second embodiment hybrid temperature control system operatesin the manner previously described in conjunction with the firstembodiment hybrid temperature control system.

[0046]FIG. 7 illustrates a third embodiment hybrid temperature controlunit 100 that includes the trailer 80, mechanical temperature controlunit 10 and supplemental cooling units 92 previously described inconjunction with first and second embodiments 50 and 90, however thethird embodiment unit 100 is related to a multi-temperature controlunit.

[0047] As illustrated in FIG. 7, the conditioned space 88 is furtherdivided into first conditioned space 88 a by lateral partition 86 and isdivided into second and third conditioned spaces 88 b and 88 c bylateral partition 87. Primary and supplemental cooling is supplied toconditioned spaces 88 a and 88 b however primary and supplementalcooling could be provided to third conditioned space 88 c as well ifdesired. One or more of the conditioned spaces may be provided withsupplemental cooling units. In operation either the first or secondspaces 88 a, 88 b may have the lowest set point temperature.

[0048] Primary mechanical evaporator 101 is flow connected to mechanicalunit in a manner well known to one skilled in the art so that duringoperation the refrigerant is supplied from unit 10 through evaporators14 and 101. Flow lines 102 a and 102 b flow connect supplementalevaporator coils 94 to tank 32. Lines 102 a and 102 b extend through theside panel 85 and bottom panel 84 of the trailer but like other linespreviously described may assume any suitable configuration.

[0049] Third embodiment hybrid temperature control unit operates in themanner previously described except that the supplemental cooling may beprovided to a conditioned space independent of other supplementalcooling units. For example, if the second conditioned space is partiallyunloaded, once the doors to the center space are closed, thesupplemental cooling may be selectively provided only to the secondconditioned space to pull down the second conditioned space and nosupplemental cooling is provided to the first conditioned space 88 a. Inthis way the cryogen is not used unnecessarily.

[0050] As illustrated in FIG. 8, the fourth embodiment hybridtemperature control unit 110 operates in the manner previouslydescribed. In the fourth embodiment, the hybrid unit 110 includes themechanical unit 10 as previously described hereinabove and also includesa supplemental cooling unit 112. The supplemental cooling unit 112 isadapted for use with the trailer 80 also previously described.

[0051] The supplemental cooling unit 112 is comprised of a cryogen tank32 with flow of the cryogen from the tank being regulated by a valve 58.In the fourth embodiment, the valve 58 is controlled by a microprocessor114. The microprocessor 114 receives a signal 115 from the mechanicalcompressor unit 11 typically via a relay or speed solenoid (not shown),corresponding to the compressor speed. When the mechanical compressor 11is in high speed cool, the microprocessor 114 sends a signal 117 to openthe valve 58, allowing the cryogen liquid to flow through thesupplemental evaporator coils 94 to provide supplemental pull down ofthe conditioned area 88 (see FIG. 6). The valve 58 will be closed if thesignal 115 received from the mechanical compressor 11 indicates that anyof the following conditions occur: the mechanical compressor enters lowspeed cool, the unit is off, the unit is in high or low speed heat orthe unit is in defrost mode.

[0052] The valve 58 will also close if the microprocessor 114 receives asignal 116 that the door to the conditioned area (not shown) is open. Inthis way, the cryogen is not wasted by cooling air that will escape fromthe trailer. The valve 58 is further controlled by a separatetemperature sensor module 118 that will send signals 120 to themicroprocessor 114 which will turn off the valve 58 if the temperatureof the gas that exits the supplemental evaporator coils 94 reaches justabove the freezing point of the cryogen, thus inhibiting the formationof dry ice in the supplemental evaporator coil 94.

[0053] The present invention hybrid temperature control system providesmany benefits and advantages over present mechanical and cryogenictemperature control units. The hybrid temperature control system of thepresent invention boosts the cooling capacity of a conventional coolingunit, and provides maximum capacity as needed, especially during initialpull-down and for quick recovery to load set point temperature afterdoor openings. By the present invention the operator may locate thecoldest cargo in any conditioned space, there is no requirement to placethe coldest cargo in the front conditioned space. Mechanical componentscan be designed to meet the more steady state cooling needs with thesupplemental evaporator providing cooling during peak loads. As a resultof the present invention the unit is quieter than equivalent mechanicalunits and weighs less than mechanical units. The physical size of thehybrid unit of the present invention is smaller than a conventionalmechanical unit with the same cooling capacity.. This is an importantbenefit since mechanical units are typically mounted on the front of thetrailer, truck or container where space is at a premium. The lowerweight unit also lowers the center of gravity of the vehicle.Engine/compressor speed can be lowered and thereby increase their usefullives. Mechanical system can be simplified to have a single speed tohandle steady state operation. This simplifies the control system andalso increases unit reliability. The present invention provides airflow,heating, defrost, and cooling for extended periods and very high coolingcapacities for rapid pull down and temperature recovery after dooropenings.

[0054] While I have illustrated and described a preferred embodiment ofmy invention, it is understood that this is capable of modification, andI therefore do not wish to be limited to the precise details set forth.

[0055] Various features and advantages of the invention are set forth inthe following claims.

What is claimed is:
 1. A method of operating a hybrid temperaturecontrol system, the method comprising: providing an evaporator, theevaporator having a discharge line, a supply line, and a evaporatorcoil, and the evaporator coil being in fluid communication with thedischarge line and the supply line; providing a microprocessor, themicroprocessor regulating a supply of a heat absorbing fluid to theevaporator; coupling a sensor module to the microprocessor, the sensormodule being near the evaporator, sensing a temperature of a gas exitingthe evaporator, and sending a temperature to the microprocessor; andturning off the supply of the heat absorbing fluid to the evaporatorwhen the microprocessor determines that the temperature of the gasexiting the evaporator reaches a predetermined temperature.
 2. Themethod of claim 1, wherein the evaporator is a supplemental evaporator,and the heat absorbing fluid is a first heat absorbing fluid, furthercomprising providing a mechanical temperature control adjacent to thesupplemental evaporator, the mechanical temperature control having aprimary evaporator coil, and the primary evaporator coil being filledwith a second heat absorbing fluid.
 3. The method of claim 1, whereinthe heat absorbing fluid is a first heat absorbing fluid, furthercomprising providing a valve, the valve being in fluid communicationwith the supply line, being regulated by the microprocessor, andregulating a supply of the first heat absorbing fluid to the supplyline.
 4. The method of claim 3, wherein the evaporator is a supplementalevaporator, and the predetermined temperature is a first predeterminedtemperature, further comprising opening the valve, thereby supplying thefirst heat absorbing fluid to the supplemental evaporator when themicroprocessor determines that the temperature of the gas exiting thesupplemental evaporator is above a second predetermined temperature. 5.The method of claim 4, wherein the second predetermined temperature isapproximately 32° F.
 6. The method of claim 3, wherein turning off thesupply of the heat absorbing fluid to the evaporator further comprisesclosing the valve, thereby turning off the supply of the first heatabsorbing fluid to the supplemental evaporator when the microprocessordetermines that the temperature of the gas exiting the supplementalevaporator reaches the first predetermined temperature.
 7. The method ofclaim 3, further comprising: receiving a compressor speed signal from acompressor; receiving a door signal from a door; opening the valve tothe supply line when the compressor speed signal indicates a firstcompressor speed; turning off the valve to the supply line when thecompressor speed signal indicates a second compressor speed; and turningoff the valve to the supply line when the door signal indicates the dooris opened.
 8. The method of claim 1, further comprising providing acryogen fluid to the heat absorbing fluid.
 9. The method of claim 8,wherein the cryogen fluid is liquid carbon dioxide, LCO₂.
 10. The methodof claim 1, wherein the first predetermined temperature is approximately−40° F.
 11. A method of operating a hybrid temperature control system,the method comprising: providing a mechanical temperature control,andthe mechanical temperature control having a primary evaporator coil;providing a supplemental evaporator, the supplemental evaporator beingadjacent to the primary evaporator coil, having a discharge line, asupply line, and a supplemental evaporator coil, the supplementalevaporator coil being in fluid communication with the discharge line andthe supply line, and the supplemental evaporator coil being filled witha second heat absorbing fluid; providing a microprocessor, themicroprocessor regulating a supply of a second heat absorbing fluid tothe evaporator; coupling a sensor module to the microprocessor, thesensor module being near the evaporator, sensing a temperature of a gasexiting the evaporator, and sending a temperature to the microprocessor;and turning off the supply of the second heat absorbing fluid to thesupplemental evaporator when the microprocessor determines that thetemperature of the gas exiting the supplemental evaporator coil reachesa predetermined temperature.
 12. The method of claim 11, furthercomprising providing a valve, the valve being in fluid communicationwith the supply line, being regulated by the microprocessor, andregulating a supply of the second heat absorbing fluid to the supplyline.
 13. The method of claim 12, wherein the predetermined temperatureis a first predetermined temperature, further comprising opening thevalve, thereby supplying the second heat absorbing fluid to thesupplemental evaporator when the microprocessor determines that thetemperature of the gas exiting the supplemental evaporator is above asecond predetermined temperature.
 14. The method of claim 13, whereinthe second predetermined temperature is approximately 32° F.
 15. Themethod of claim 12, wherein turning off the supply of the second heatabsorbing fluid to the supplemental evaporator further comprises closingthe valve, thereby turning off the supply of the second heat absorbingfluid to the supplemental evaporator when the microprocessor determinesthat the temperature of the gas exiting the supplemental evaporatorreaches the first predetermined temperature.
 16. The method of claim 15,wherein the first predetermined temperature is approximately −40° F. 17.The method of claim 12, further comprising: receiving a compressor speedsignal from a compressor; receiving a door signal from a door; openingthe valve to the supply line when the compressor speed signal indicatesa first compressor speed; turning off the valve to the supply line whenthe compressor speed signal indicates a second compressor speed; andturning off the valve to the supply line when the door signal indicatesthe door is opened.
 18. The method of claim 11, further comprisingproviding a cryogen fluid to the heat absorbing fluid.
 19. The method ofclaim 11, wherein the second heat absorbing fluid is liquid carbondioxide, LCO₂.
 20. A hybrid temperature control system, the systemcomprising: a mechanical temperature control, the mechanical temperaturecontrol including a primary evaporator having a first evaporator coilbeing filled with a first heat absorbing fluid; a supplementalevaporator located adjacent to the first evaporator coil, thesupplemental evaporator having a discharge line, an inlet line, and asupplemental evaporator coil, the supplemental evaporator coil in fluidcommunication with the discharge line and the inlet line, and thesupplemental evaporator coil being filled with a second heat absorbingfluid; a sensor module positioned near the supplemental evaporator, thesensor module sensing a temperature of a gas exiting the evaporator; anda microprocessor operatively coupled to the sensor module, themicroprocessor receiving a temperature from the sensor module,regulating a supply of the second heat absorbing fluid, turning off thesupply of the second heat absorbing fluid to the supplemental evaporatorwhen the microprocessor determines that the temperature of the gasexiting the evaporator reaches a predetermined temperature.
 21. Thesystem of claim 20, further comprising: a valve being in fluidcommunication with the supply line, being regulated by themicroprocessor, and regulating a supply of the second heat absorbingfluid to the supply line.
 22. The system of claim 21, wherein the valveis substantially closed, thereby turning off the second heat absorbingfluid to the supplemental evaporator when the microprocessor determinesthat the temperature of the gas exiting the supplemental evaporatorreaches the predetermined temperature.
 23. The system of claim 20,wherein the predetermined temperature is approximately −40° F.
 24. Thesystem of claim 20, further comprising: a compressor, the compressorsending a compressor speed signal to the microprocessor; themicroprocessor opening the valve to the supply line when the compressorspeed signal indicates a first compressor speed, and turning off thevalve to the supply line when the compressor speed signal indicates asecond compressor speed; and a door, the door sending a door signal tothe microprocessor, turning off the valve to the supply line when thedoor signal indicates the door is opened.
 25. The system of claim of 20,wherein the valve is substantially opened, thereby supplying the secondheat absorbing fluid to the supplemental evaporator when themicroprocessor determines that the temperature of the gas exiting thesupplemental evaporator is above a second predetermined temperature. 26.The system of claim 25, wherein the second predetermined temperature isapproximately 32° F.
 27. The system of claim 20, wherein the second heatabsorbing fluid is liquid carbon dioxide, LCO₂.
 28. A retrofittemperature control system, the system comprising: a supplementalevaporator retrofitted adjacent to a first evaporator coil of anexisting temperature control system, the supplemental evaporator havinga discharge line, an inlet line, and a supplemental evaporator coil, thesupplemental evaporator coil in fluid communication with the dischargeline and the inlet line, and being filled with a heat absorbing fluid; asensor module positioned near the supplemental evaporator, the sensormodule sensing a temperature of a gas exiting the evaporator; and amicroprocessor operatively coupled to the sensor module, themicroprocessor receiving a temperature from the sensor module,regulating a supply of the heat absorbing fluid, turning off the supplyof the heat absorbing fluid to the supplemental evaporator when themicroprocessor determines that the temperature of the gas exiting theevaporator reaches a predetermined temperature.
 29. The system of claim28, further comprising: a valve being in fluid communication with thesupply line, being regulated by the microprocessor, and regulating asupply of the heat absorbing fluid to the supply line.
 30. The system ofclaim of 29, wherein the valve is substantially opened, therebysupplying the second heat absorbing fluid to the supplemental evaporatorwhen the microprocessor determines that the temperature of the gasexiting the supplemental evaporator is above a second predeterminedtemperature.
 31. The system of claim 29, wherein the valve issubstantially closed, thereby turning off the second heat absorbingfluid to the supplemental evaporator when the microprocessor determinesthat the temperature of the gas exiting the supplemental evaporatorreaches the predetermined temperature.
 32. The system of claim 28,wherein the predetermined temperature is approximately −40° F.
 33. Thesystem of claim 28, wherein the existing temperature control systemfurther comprises: a compressor, the compressor sending a compressorspeed signal to the microprocessor; the microprocessor opening the valveto the supply line when the compressor speed signal indicates a firstcompressor speed, and turning off the valve to the supply line when thecompressor speed signal indicates a second compressor speed; and a door,the door sending a door signal to the microprocessor, turning off thevalve to the supply line when the door signal indicates the door isopened.
 34. The system of claim 31, wherein the second predeterminedtemperature is approximately 32° F.
 35. The system of claim 28, whereinthe heat absorbing fluid is a cryogen fluid.
 36. The system of claim 35,wherein the cryogen fluid is liquid carbon dioxide, LCO₂.
 37. A methodof retrofitting a temperature control system, the method comprising:providing an existing temperature control system; and retrofitting asupplemental evaporator with the existing temperature control system,the evaporator having a discharge line, a supply line, and a evaporatorcoil, the evaporator coil being in fluid communication with thedischarge line and the supply line, and the evaporator coil being filledwith a heat absorbing fluid;
 38. The method of claim 37, wherein theexisting temperature control system is a mechanical temperature controlsystem, further comprising locating the mechanical temperature controladjacent to the supplemental evaporator, the mechanical temperaturecontrol having a primary evaporator coil, and the primary evaporatorcoil being filled with a second heat absorbing fluid.
 39. The method ofclaim 37, wherein the heat absorbing fluid is a first heat absorbingfluid, further comprising: providing a valve, the valve being in fluidcommunication with the supply line, being regulated by a microprocessor;coupling a sensor module to the microprocessor, the sensor module beingnear the supplemental evaporator, sensing a temperature of a gas exitingthe supplemental evaporator, and sending a temperature to themicroprocessor; and turning off the supply of the heat absorbing fluidto the evaporator when the microprocessor determines that thetemperature of the gas exiting the evaporator reaches a predeterminedtemperature.
 40. The method of claim 39, wherein turning off the supplyof the heat absorbing fluid to the evaporator further comprises closingthe valve, thereby turning off the supply of the first heat absorbingfluid to the supplemental evaporator when the microprocessor determinesthat the temperature of the gas exiting the supplemental evaporatorreaches the first predetermined temperature.
 41. The method of claim 39,further comprising: receiving a compressor speed signal from acompressor; receiving a door signal from a door; opening the valve tothe supply line when the compressor speed signal indicates a firstcompressor speed turning off the valve to the supply line when thecompressor speed signal indicates a second compressor speed; and turningoff the valve to the supply line when the door signal indicates the dooris opened.
 42. The method of claim 39, wherein the predeterminedtemperature is a first predetermined temperature, further comprisingopening the valve, thereby supplying the first heat absorbing fluid tothe supplemental evaporator when the microprocessor determines that thetemperature of the gas exiting the supplemental evaporator is above asecond predetermined temperature.
 43. The method of claim 42, whereinthe second predetermined temperature is approximately 32° F.
 44. Themethod of claim 37, further comprising providing a cryogen fluid to theheat absorbing fluid.
 45. The method of claim 44, wherein the cryogenfluid is liquid carbon dioxide, LCO₂.
 46. The method of claim 37,wherein the first predetermined temperature is approximately −40° F.